This invention relates to a device for transferring and applying sealing bands. More particularly, the invention relates to a device for transferring gummed sealing bands to a line feeding substantially parallelepiped packets, such as cigarette packets.
In cigarette packeting machines, it is known to normally apply to the finished packet sealing band which are withdrawn by a feed device from the bottom of a pile superposed bands or cut in succession from a continuous strip.
In known feed devices, each sealing bands is withdrawn by a conveyor roller which inserts it into the top of a vertical guide defined by a plurality of pairs of side-by side rollers. During the descent of the bands, which takes place in the direction of their longitudinal dimension along said guide, each band is gummed along its surface by gumming devices, and is finally fed into a pocket which has a side withdrawal aperture facing the ungummed surface of the band. Each band is retained by suction within said pocket, from which it is withdrawn through said aperture by a fork element. This fork element comprises two branches which are provided with suction means arranged to cooperate with the two longitudinal ends of the sealing bands housed in said pocket. These arms are able to traverse normal to the plane of said aperture in order to extract the band from the pocket and then undergo a movement involving rotation of said fork in order to transfer the band to its position of application located on a path followed by the packets.
Each pocket, when moving through the arms of the fork element at the position of application, comes into contact with the gummed surface of the sealing band extended between the arm. In this manner the band separates from the fork and adheres to the leading end of the packet.
A drawback of devices of the aforesaid type is that the fork element often encounters difficulty in extracting the bands from said pocket.
This drawback, which can result in no extraction of the bands and thus interruption in their feed to the packets, occurs particularly frequently in the case of bands having their longitudinal dimension exceeding a determined limit. This is so in the case of sealing bands which are to be applied in the direction of the longitudinal dimension of the end of the cigarette packets instead of in the more common transverse position.